1. Field of the Invention
The present invention generally relates to a control apparatus and a method for actuating an electrically driven compressor used in an air conditioning system of an automotive vehicle, which is capable of promptly and adequately adjusting the output of the compressor in response to a detected increase of the inside or peripheral temperature of the control system, thereby stabilizing the operation of the compressor and assuring reliability of the air conditioning system.
2. Prior Art
A control system of an electric compressor is generally subjected to heat generation due to power consumption when it actuates the compressor. For example, an electrically driven compressor, when it has an output of 2 KW, will cause a heat generation of approximately 40 W which corresponds to 2% of the overall output. Various electronic components inside the control system are sensitive to heat; thus, it is essentially important to protect these electronic components for guaranteeing the performance of the control system. To this end, the control system is generally provided with a heat radiation device of normally an air-cooling type or a water-cooling type. Specifications of the heat radiation device needs to be designed based on the heat radiation conditions including ambient or peripheral temperatures and electric power consumption.
Furthermore, in the event of unusual increase of temperature, some of electrically driven compressor can be automatically stopped to prevent any damage from occurring by such excessive heat generations.
According to the above-described conventional systems, when the temperature of the control system is extraordinarily increased, the only effective countermeasure is to stop the electric compressor; otherwise, the control system of the electric compressor will be fatally damaged.
However, in view of the driving safety, sudden stop or malfunction of an air conditioning system in an automotive vehicle is not desirable and recommendable. For example, sudden stop of the air conditioning system will make it impossible to keep a clean view through the front windshield glass since the glass will be clouded up with moisture. Furthermore, a drive or passenger may be surprised or frightened by the sudden stop of blow air. Needless to say, such sudden stop or malfunction will make passengers feel uncomfortable.
Still further, it is essentially important to assure a long life of the control system of each electric compressor. In this respect, an electrolytic capacitor, which essentially determines the life of the electric compressor control system since its life is significantly short, needs to be kept safely so as not to suffer from increase of temperature.